streams/readable-streams/global.html

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<title>Ensure Stream objects are created in expected globals. </title>

<script src="/resources/testharness.js"></script>
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// These tests are loosely derived from Gecko's readable-stream-globals.js,
// which is a test case designed around the JS Streams implementation.
//
// Unlike in JS Streams, where function calls switch realms and change
// the resulting global of the resulting objects, in WebIDL streams,
// the global of an object is (currently underspecified, but) intended
// to be the "Relevant Global" of the 'this' object.
//
// See:
// https://html.spec.whatwg.org/multipage/webappapis.html#relevant
// https://github.com/whatwg/streams/issues/1213
"use strict"

const iframe = document.createElement("iframe")
document.body.append(iframe)

const otherGlobal = iframe.contentWindow;
const OtherReadableStream = otherGlobal.ReadableStream
const OtherReadableStreamDefaultReader = otherGlobal.ReadableStreamDefaultReader;
const OtherReadableStreamDefaultController = otherGlobal.ReadableStreamDefaultController;

promise_test(async () => {

    // Controllers
    let controller;
    let otherController;

    // Get Stream Prototypes and controllers.
    let streamController;
    let stream = new ReadableStream({start(c) { streamController = c; }});

    const callReaderThisGlobal = OtherReadableStream.prototype.getReader.call(stream);
    const newReaderOtherGlobal = new OtherReadableStreamDefaultReader(new ReadableStream());

    // Relevant Global Checking.
    assert_equals(callReaderThisGlobal instanceof ReadableStreamDefaultReader, true, "reader was created in this global (.call)");
    assert_equals(newReaderOtherGlobal instanceof ReadableStreamDefaultReader, false, "reader was created in other global (new)");

    assert_equals(callReaderThisGlobal instanceof OtherReadableStreamDefaultReader, false, "reader isn't coming from other global (.call)" );
    assert_equals(newReaderOtherGlobal instanceof OtherReadableStreamDefaultReader, true, "reader isn't coming from other global (new)");

    assert_equals(otherController instanceof ReadableStreamDefaultController, false, "otherController should come from other gloal")


    const request = callReaderThisGlobal.read();
    assert_equals(request instanceof Promise, true, "Promise comes from this global");

    streamController.close();
    const requestResult = await request;
    assert_equals(requestResult instanceof Object, true, "returned object comes from this global");
}, "Stream objects created in expected globals")

promise_test(async () => {
    const stream = new ReadableStream();
    const otherReader = new OtherReadableStreamDefaultReader(stream);
    const cancelPromise = ReadableStreamDefaultReader.prototype.cancel.call(otherReader);
    assert_equals(cancelPromise instanceof Promise, true, "Cancel promise comes from the same global as the stream");
    assert_equals(await cancelPromise, undefined, "Cancel promise resolves to undefined");
}, "Cancel promise is created in same global as stream")

// Refresh the streams and controllers.
function getFreshInstances() {
    let controller;
    let otherController;
    let stream = new ReadableStream({
        start(c) {
            controller = c;
        }
    });

    new OtherReadableStream({
        start(c) {
            otherController = c;
        }
    });

    return {stream, controller, otherController}
}


promise_test(async () => {
    // Test closed promise on reader from another global (connected to a this-global stream)
    const {stream, controller, otherController} = getFreshInstances();

    const otherReader = new OtherReadableStreamDefaultReader(stream);
    const closedPromise = otherReader.closed;
    assert_equals(closedPromise instanceof otherGlobal.Promise, true, "Closed promise in other global.");
}, "Closed Promise in correct global");

promise_test(async () => {
    const {stream, controller, otherController} = getFreshInstances();

    const otherReader = OtherReadableStream.prototype.getReader.call(stream);
    assert_equals(otherReader instanceof ReadableStreamDefaultReader, true, "Reader comes from this global")
    const request = otherReader.read();
    assert_equals(request instanceof Promise, true, "Promise still comes from stream's realm (this realm)");
    otherController.close.call(controller);
    assert_equals((await request) instanceof otherGlobal.Object, true, "Object comes from other realm");
}, "Reader objects in correct global");


promise_test(async () => {
    const {stream, controller, otherController} = getFreshInstances();
    assert_equals(controller.desiredSize, 1, "Desired size is expected");
    Object.defineProperty(controller, "desiredSize",
        Object.getOwnPropertyDescriptor(OtherReadableStreamDefaultController.prototype, "desiredSize"));
    assert_equals(controller.desiredSize, 1, "Grafting getter from other prototype still returns desired size");
}, "Desired size can be grafted from one prototype to another");

promise_test(async () => {
    const {stream, controller, otherController} = getFreshInstances();

    // Make sure the controller close method returns the correct TypeError
    const enqueuedError = { name: "enqueuedError" };
    controller.error(enqueuedError);

    assert_throws_js(TypeError, () => controller.close(),  "Current Global controller");
    assert_throws_js(otherGlobal.TypeError, () => otherController.close.call(controller),  "Other global controller");
}, "Closing errored stream throws object in appropriate global")

promise_test(async () => {
    const {otherController} = getFreshInstances();
    // We can enqueue chunks from multiple globals
    const chunk = { name: "chunk" };

    let controller;
    const stream = new ReadableStream({ start(c) { controller = c; } }, { size() {return 1} });
    otherController.enqueue.call(controller, chunk);
    otherController.enqueue.call(controller, new otherGlobal.Uint8Array(10));
    controller.enqueue(new otherGlobal.Uint8Array(10));
}, "Can enqueue chunks from multiple globals")

promise_test(async () => {
    const {stream, controller, otherController} = getFreshInstances();
    const chunk = { name: "chunk" };

    // We get the correct type errors out of a closed stream.
    controller.close();
    assert_throws_js(TypeError, () => controller.enqueue(new otherGlobal.Uint8Array(10)));
    assert_throws_js(otherGlobal.TypeError, () => otherController.enqueue.call(controller, chunk));
    assert_throws_js(otherGlobal.TypeError, () => otherController.enqueue.call(controller, new otherGlobal.Uint8Array(10)));
}, "Correct errors and globals for closed streams");


promise_test(async () => {
    const {stream, controller, otherController} = getFreshInstances();
    // Branches out of tee are in the correct global

    const [branch1, branch2] = otherGlobal.ReadableStream.prototype.tee.call(stream);
    assert_equals(branch1 instanceof ReadableStream, true, "Branch created in this global (as stream is in this global)");
    assert_equals(branch2 instanceof ReadableStream, true, "Branch created in this global (as stream is in this global)");
}, "Tee Branches in correct global");
</script>